Automatic slack adjuster for brakes



Jilly 17, 1923.

' A. R. K. DJURSON AUTOMATIC SLACK ADJUSTER FOR BRAKES Filed April 27.1921 Patented July 17,1923.

FATE

owner..

AXEL BUDOLF KONRAD DJURSON, OF MALT/IO, SVEDEN, ASSIGNOR' '10 SVENSKA.AKTIEBOLAGET BROMSREG'ULATOR, OF STOCKHOLM, SWEDEN, 'A COMPANY.

AUTOMATIC SLACK ADJUSTER FOR BRAKES.

Application filed-April 27, 1921. Serial No. 464,864.

T 0 all whom it may concern Be it known that I, AXEL RUDo r Kon- RADDJURSON, a citizen of Sweden, residing at Malmo, in the county ofMalmohus, Sweden, have invented certain new and useful Improvements inAutomatic Slack Adjusters for Brakes, of which the following is aspecification.

My invention relates to automatic slackadjusters for brakes of the typeshown for example in Patent No. 128363 1, November 5,

1918, in which a feeding deviceis arranged in the brake mechanisnn whichfeeding de vice acts upon a turnbuckle or other suitable take-up devicefor. reducing. the play, the feeding device being connected with ayielding member which, when friction arising in the mechanism by theincreasing brake pressure stops further movement of the same, absorbsthe rest of the movement of the feeding device during the brakingoperation. Devices of this kind are already known.

The continual transmission of the'movement of the brake mechanism to theslackadjuster is, however, affected with several disadvantages, whichare removed by the present invention. i

' As taking-up of the slack always must be done at the cost of a certainincrease of the stroke of the piston of the brake cylinders or acorresponding member and it is very important that this increase is assmall as possible, it is of course very desirable that the period duringwhich takingup of the slack takes place causes the smallest possibleincrease of the stroke, which increase in slack-adjusters of the kindmentioned above hitherto used always is proportional to the size of theslack to be taken up.

Besides, the movement of the driving member acting upon theslack-adjuster ought to be limited as much as possible in order.

to prevent that the yielding member of the slack-adjuster will be toomuch strained.

Finally, the slack adjuster ought to return toits starting position assoon as possible when loosening the brake, so that it has time to reachthis position, before the piston or corresponding member has returned toits starting position, because the springs or the like, wh ch bring thesa e back to i s start:

ing-position, oftenly do not function satisfactorily but allow thepiston in the brakecylinder to stop before this position is reached.Then if it should happen that the slack-adjuster has not returned to itsstart ing-positionbefore the piston has finished its return movement theslack-adjuster will begin to work with the new position of the piston asstarting-position, which means increased slack.

Moreover, as the piston rod only'exceptionally is provided with parallelguides the mechanism of the slack-adjuster will always be influenced byand dependent on thp1 eventual side movements of the piston ro Thesedisadvantages are removed by the present invention by giving theslack-adjuster a discontinual movement differine from and independent ofthe movements of the piston rod orv the corresponding memher as well inlongitudinal direction as lat-- erally. These lateral movements of thepiston rod are incident to the play of the piston or rod due tolooseness where the rod is not eXteriorly guidedf V p In theaccompanying drawing Fig. 1 is a side view of the slack-adjustingmechanism according to the invention and Fig. 2 is an end elevationthereof.

The numeral 1 designates the brake cylinder, 2 is the brake piston, 3the piston rod and 1 the spring that brings the piston back to itsstarting position. The levers 5, 6 are in the usual way connected withthe brake cylinder 1 and the piston rod 3 and connected with each otherby means of the rod 7. At the ends most remote from the brake cylindersaid levers are connected with the brake rods 8, 9 leading to the brakeblocks. The conventional slackndiuster 10 is placed on one of theserods9. On theouter end of the piston rod or on some other suitable part ofthe brake mechanism roller 11 is provided, said roller running lna slot12' rod 15 are guided by the member 13 and are connected with each otherby means of a link or the like 17. The guide 13 is pivotally connectedwith some part 01. the truck by means of a rod 18 and a pin 19 insuch a.way that itis prevented from moving in the longitudinal direction butallowed to take part in the lateral loose play movements of the pistonrod. The longer the rod 18 in relation to the distance between therolers 11 and 1 1, the more the influence of the lateral movements ofthe piston rod on the crank 16 is reduced.

The slot 12 in the guide 13 is not straight but provided with an obliquepart 20 arranged in such a relation to the crank 16 on theslaclcadjuster that when the roller 14 on the end of the connecting rod15 passes through the same at the movement of the brake piston 2 theslack-adjuster will be acted upon for taking up an eventual too largeslack. By giving the link 17 a suitable length, so that the roller 14.-is placed at a distance from the oblique part 20 of the slot 12corresponding to the desired slack, the extent of the slack may easilybe predetermined.

The operation of the device described is as follows. lVhenbrali'ingtakes place the brake piston is moved and also the roller 14 indirection towards the oblique part 20 of the slot 12. When this movementhas proceeded so far as to correspond to the predetermined slack theroller 14 has reached the oblique part of the slot, and at furthermovement the connecting" rod 15 will be moved upwards whereat he crank16 of the slack-adjuster is turned If the slack should happen to begreater than the predetermined slack a screwing together of the slackadjuster takes place and thus also a reduction of the slack. 011 thecontrary, if the slack is normal the brake blocks will rest against thewheels at the same moment as the roller 1 1- arrives to the oblique part20 of the slot in the guide, whereat strain arises in the brakemechanism and thus also in the slack-adjuster 10, so that the frictionin the latter in a known way prevents the same "from turning in relationto the rod 9 and thus stops a further taking up of the slack. In thiscase the continued turning of the crank is taken up by the yieldingmember in the slack-adjuster.

By increasing the angle formed by the oblique part 20 in relation to therest of the slot 12 a large movement of the crank 16 in relation to themovement of the brake piston is obtained, which as shown above isimportant for obtaining a stroke as constant as possible.

As the roller 14- when the broke is loosened is forced to follow theslanting slot 20 the slack-adjuster returns to its starting-positionbefore the brake piston, whereby is ensured that it does not have anyeffect upon the operation of the slack-adjuster, it the brake piston, asoften is the case, should not completely return.

By limiting the inclined part 20 of the slot in the guide an unnecessary.overstrain of the yieldin member in the slaclcadjuster is excluded.

Further it is evident that the influence of the eventual lateralmovements of the piston rod will be eliminated which is of a greatimportance, especially as the piston rod often is not guided.

The new invention has also the advantage that the slack may bedetermined before, hand easily and correctly.

Having described my invention, What I claim is 1. An air brakecontroller having; a piston rod, a slack adjuster, a member foroperating the slack adjuster, a guide formed with a slot slidablyreceiving 'a connection from said member and a connection from saidpiston rod, said guide being movably mounted to respond to loose play ofthe piston rod, said guide being formed to positively operate saidmember in a predetermined movement of the piston rod.

2. An air brake controller having a piston rod, a slack adjuster, amember for operating; the slack adjuster, a guide formed with a slotslidably receiving a connection from said member and a connection fromsaid piston rod, means joining said connections, said guide beingmovably mounted to respond to loose play of the piston rod, said guidebeing formed to positively operate said member in a predeterminedmovement of the piston rod.

3. An air brake controller having a piston rod, a slack adjuster, amember for operating the slack adjuster, a guide formed with a slotslidably receiving a connection from said member and a connection fromsaid piston rod, means joining said connections, said guide beingmovablv mounted to respond to loose play of the piston rod, said slothaving an inclined portion positively operate said member for slackadjustment in a predetermined movement of the piston rod.

4. An air brake controller having a piston rod, a slack adjuster, amember for operating the slack adjuster, a guide formed with a slotslidably receiving a connection from from said member and a connectionfrom said piston rod, means joining Sk -id connections, said guide beingmovably mounted to respond to loose play of the piston rod, said slothaving a straight portion normally receiving the piston rod connectionand member connection and an in In testimony whereof, I have signed myname to this specifioation in the presence 10 of two subscribingWitnesses.

AXEL RUDOLF KONRAD DJURSON.

1 Witnesses: r

ERNST PERSON, G. Pn'rnnsson.

